> ## Documentation Index
> Fetch the complete documentation index at: https://docs.onchainbrews.wtf/llms.txt
> Use this file to discover all available pages before exploring further.

# Randomization

> Every held token is eligible for a share of future rewards. Randomization is fully trustless and on-chain.

### Randomness

For an eligible token, the contract derives `randomTokenId` from `H("holder", seed)` mod `supplyAtMint` (with a one-step re-roll if it equals the minter’s own token and supply > 1). The rweard for`ownerOf(randomTokenId)`occurs at claim time, which means that *the reward will be sent to whomever is holding the token when the reward is claimed.*

### Eligibility

A token’s reward outcome is determined **one block after** it’s been minted using `blockhash(mintBlock)`. Because the mint block's hash is not determined until the block is finalized and minting block is sealed, no one can know the outcome.

Ethereum exposes `blockhash` only for the last 256 blocks; if a claim is attempted after that, `blockhash(mintBlock) == 0` and the token is **not eligible**.

<Info>
  Currently, a bot is processing rewards automatically. As an on-chain fallback, anyone can call the "claim" function and trigger the distribution of rewards within the 256-block window.
</Info>

### Fairness

Each token draws a reward  using`seed = keccak256(tokenId, blockhash(mintBlock))`. The contract first checks for a big reward; if the token is not elibile, the contract re-rolls for a small reward.

```solidity theme={null}
function _drawReward(uint256 seed) internal pure returns (Reward) {
	uint256 rBig = uint256(keccak256(abi.encodePacked("big", seed)));
        if (rBig % BIG_ODDS == 0) 
			return Reward.Big;
   	uint256 rSml = uint256(keccak256(abi.encodePacked("small", seed)));
        if (rSml % SMALL_ODDS == 0) 
			return Reward.Small;
        return Reward.None;
    }
```